One-shot-oriented event timers management

[Alexander Motin]

Alexander Leidinger wrote:
> Quoting Alexander Motin <mav at FreeBSD.org> (from Sun, 29 Aug 2010
> 16:10:00 +0300):
> 
>> I have actively tested this code for a few days on my amd64 Core2Duo
>> laptop and i386 Core-i5 desktop system. With C2/C3 states enabled
>> systems experience only about 100-150 interrupts per second, having HZ
>> set to 1000. These events mostly caused by several event-greedy
>> processes in our tree. I have traced and hacked several most aggressive
>> ones in this patch: http://people.freebsd.org/~mav/tm6292_idle.patch .
>> It allowed me to reduce down to as low as 50 interrupts per system,
>> including IPIs!
> 
> It looks like you are comming to a point where Powertop would be
> helpful. There's a dtracified version of it available at the opensolaris
> site (it would at least need some additional dtrace probes in our kernel).
> 
> http://hub.opensolaris.org/bin/view/Project+tesla/Powertop

Thank you for the link. I was thinking about it, but worried that it
could be too Linux-specific. Nice to here there is closer alternative.
I'll look on it.

PS: Until it is ported, I've found that `top -m io -o vcsw` could also
be useful. The only thing it can't show is in-kernel callout(9) calls.
User and kernel processes wakeups still nicely visible there.

-- 
Alexander Motin